This invention relates to fluorescent lighting fixtures and particularly to methods for the cooling of lamps operating within such fixtures.
In an effort to conserve energy, limit pollution produced by electricity generating facilities and reduce costs to energy consumers, the use of fluorescent lamps instead of incandescent lamps is rapidly gaining acceptance for the lighting of commercial and residential interiors. To the same end, efforts have been made to improve on the efficiency of fluorescent lamps. Most efforts have focused on developing more efficacious lamps and ballasts and improved energy management. While the aforementioned efforts are often meritorious, often overlooked are methods for increasing the fixture efficiency.
Various methods for increasing fixture efficiency are known in the art. These are generally complex. Reference is made to the devices described in U.S. Pat. Nos. 3,112,890 and 3,869,606.
Other techniques for increasing efficiency focus on reducing the lamp wall temperature of a fluorescent bulb while a fluorescent bulb is housed inside fluorescent bulb fixture. This technology has developed since it is known that fluorescent lamps efficiency is highly sensitive to changes in minimum lamp wall temperature. For the standard F40 lamp/CBM (Certified Ballast Manufacturers) ballast system, light output is maximal at a MLWT of 37.degree. C. (.+-.1.degree.), corresponding to an ambient temperature of 25.degree. C. This is also the temperature condition at which manufacturers rate the lamp's lumen output.
To the end of reducing lamp wall temperatures, techniques include optimization of the thermal operating characteristics of a fluorescent lamp system. For example, techniques such as lamp compartment air flow fixtures and natural convention cooling of the lamp compartment have been developed. Also, described in U.S. patent application Ser. No. 07/516,767, filed Apr. 30, 1990, naming one of the applicants as inventor, is an invention directed to direct lamp spot cooling using thermoelectric and heat pipe devices. Reference is also made to an article by one of the instant inventors, Siminovitch, Michael, Energy Conservation from Thermally Efficient Fluorescent Fixtures, in Strategic Planning and Energy Management, Vol. 9, No. 3, 1990 for an overview of the research involved in the development of the invention described in the aforementioned patent application.
While the techniques discussed above address the optimization of thermal operating characteristics of a fluorescent lamp system, several of the systems described require that heat be transferred to and dissipated from a plenum located above the fluorescent lamp system. This further requires that the lamp system be mounted into a ceiling, or at least, be mounted so that the heat generated from the lamp be allowed access to the plenum above the ceiling.
The invention disclosed in U.S. patent application Ser. No. 07/516,767, as described above, is best suited for tube fluorescent light bulbs. However, compact fluorescent light bulbs are also commonly used in the lighting industry. Therefore, it is highly desirable to invent a thermally optimized fluorescent lamp system which, in its embodiment, is applicable to both tube fluorescent light bulbs and compact fluorescent light bulbs lamp systems.
It is also desirable, in an effort to optimize thermal operating characteristics of a lamp system, to be able to retrofit already existing lamp systems with a minimal expense of reconfiguration. It is further desirable to minimize costs of thermal optimization in new lamp systems.